1. Field of the Invention
This invention relates to a method for manufacturing reinforced thermoplastic pipes used in transporting fluids and gasses.
2. Description of the Related Art
Transporting fluids (or even gasses), such as water and chemicals can be costly and time consuming. For example, in today's energy scarce environment, efficient oil and gas recovery techniques are vital. One means for inducing recovery is using an induced hydraulic fracturing method. “Fracturing fluids” or “pumping fluids” or “fracking fluids” consisting primarily of water and sand are injected under high pressure into the producing formation, creating fissures that allow resources to move freely from rock pores where it is trapped. Chemicals can be added to the water and sand mixture (creating a slickwater) to increase the fluid flow. Fractures provide a conductive path connecting a larger area of the formation to the well, thereby increasing the area from which natural gas and liquids can be recovered from the targeted formation.
Water for the fracturing method is supplied to the recovery site (and perhaps the fluid's byproduct from the fracturing method, known sometimes as flowback water, removed from the site) by a piping system. The piping system can consist of hundreds or thousands of yards of pipes. The piping system could include hundreds of pipes joined together by couplers to form the overall piping system. Although technically effective, environmentalists are concerned that fracking fluids may leak from the piping system thus causing damage to the environment. Consequently, many areas where oil and gas reservoirs exist may not be exploited due to environmental concerns.
Traditional pipes used for transporting fluids, such as water, are made of steel or other metals, such as aluminum. More recent pipes are composed of a plastic material such as high density polyethylene (HDPE). HDPE pipes have some advantages over metal pipes, including lower costs, abrasion resistance, corrosion resistance, high impact resistance and greater flexibility (which are especially useful over uneven terrains). These pipes are durable for gas, chemical and water applications and may be reused.
For example, a typical Yelomine™ pipe has a weight density of 300 pounds (lbs.) per 30 feet (ft.) of length. This pipe has moderate durability but needs support structure (such as support blocks) during fluid transport use.
A typical aluminum pipe used in today's fluid transport system is light weight with a weight density of 90 lbs./30 ft. of length. However it is not very durable and like the Yelomine™ pipe requires a support system during the fluid transfer. It has a pressure to weight ratio of a little more than 1.
Although HDPE pipes are in current use, such current use includes thick walled HDPE pipes, such as a DR9 HDPE pipe. To ensure the integrity of the piping system under high fluid transport pressure, the walls of the HDPE pipes are typically more than an inch thick. For example, the DR9 HDPE pipe has a wall thickness of 1.11 inches. The DR9 HDPE pipe has a weight density of a whopping 650 lbs./30 ft. It is highly durable but costs nearly 3 times more than an aluminum pipe. The pipes are difficult to transport in rough, uneven or forest terrains. Often, trucks or other mechanical movers are needed to transport the heavy pipes for construction of the system. These pipes are typically buried and then are not reusable. The pressure to weight ratio of the DR9 HDPE pipe is less than 0.4. Consequently, although thick walled HDPE pipes may be more durable then aluminum or Yelomine™ pipes, current thick walled HDPE pipes in industrial use remain very heavy. Furthermore, coupling these individual thick walled pipes to create the piping system may be slow and burdensome. That is, butt fusing systems are often used to join thick walled pipes. The use of the butt fusing system is often time consuming due to its process and the heavy equipment needed to be transported to the installation site for the connection of the pipes. In addition, as a result of environmental concerns, a coupler-less piping system or a system with few couplers is desirable since most leaks occur at a coupler or joint. Consequently, the use of current thick walled HDPE pipes may not be feasible in transporting liquids or gas over a great distance or through rough terrain under high pressure.
What is needed is a lightweight and cost effective HDPE piping system that can, among other things, withstand the environment and gas and fluid pressures of current oil and gas recovery methods. The novel system needs to be designed and constructed for easy transport and installation. The lightweight pipes can be lifted and carried by 2 men. The novel system needs to provide a high flow and a high strength solution. The system needs to allow for minimal blocks or a support system in an above ground application. Rather, the novel piping system can lie on the ground during use or span voids. However, below ground installation is not restricted by the novel system. Since the novel system can be made with a thermoplastic, such as HDPE, the piping system may be resistant to theft (since metal pipes are often stolen).
In addition, the novel system may be used for other applications, such as water irrigation or temporary supply of water or removal of waste during emergencies or gas and chemical transport.